The present invention relates to a passive laser accelerometer which utilizes a laser external of a resonant cavity having a birefringent material therein which produces a pair of orthoganally polarized beams differing in phase.
Other laser accelerometers are known in which the laser source is positioned in the resonant cavity which results in mode locking problems. Under low input accelerations the phases of the two oscillations lock-together and the output beat frequency remains unchanged. To obtain an output the birefringent material must be stressed beyond the lock-in value.
Additionally, mounting the birefringent material in the resonant cavity provides residual strains in the birefringent material and the laser and birefringent material are in such close proximity that the birefringent is heated, creating more undesirable residual strains in the birefringent material.
In one embodiment of the invention the system is implemented in an integrated optics format. The principle of integrated optics is disclosed in the publication "Spectrum", pages 22-29, December 1978, entitled "Integrated Optical Spectrum Analyzer: an Imminent Chip".